Few syntheses of mononuclear isothiazoles have been described.
W. R. Hatchard in Journal of Organic Chemistry, 29, pp. 660-668, teaches the synthesis of 3,5-dichloro-4-isothiazolecarbonitrile by the treatment of di(sodiomercapto)methylenemalononitrile with excess chlorine in boiling carbon tetrachloride. Hatchard also teaches reacting the salts of dimercaptomethylenemalononitrile with sulfur in boiling methanol to form salts of 3,5-dimercapto-4-isothiazolecarbonitrile, which in turn are converted to a variety of alkylthio-, acylthio-, and alkylsulfonylisothiazolecarbonitrile derivatives.